reference : Effects of temperature on the transmission of West Nile virus by Culex tarsalis (Diptera: Culicidae)

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reftype Journal Article
Abstract Culex tarsalis Coquillett females were infected with the NY99 strain of West Nile virus (family Flaviviridae, genus Flavivirus, WNV) and then incubated under constant temperatures of 10-30 degrees C. At selected time intervals, transmission was attempted using an in vitro capillary tube assay. The median time from imbibing an infectious bloodmeal until infected females transmitted WNV (median extrinsic incubation period, EIP50) was estimated by probit analysis. By regressing the EIP rate (inverse of EIP50) as a function of temperature from 14 to 30 degrees C, the EIP was estimated to require 109 degree-days (DD) and the point of zero virus development (x-intercept) was estimated to be 14.3 degrees C. The resulting degree-day model showed that the NY99 WNV strain responded to temperature differently than a lineage II strain of WNV from South Africa and approximated our previous estimates for St. Louis encephalitis virus (family Flaviviridae, genus Flavivirus, SLEV). The invading NY99 WNV strain therefore required warm temperatures for efficient transmission. The time for completion of the EIP was estimated monthly from temperatures recorded at Coachella Valley, Los Angeles, and Kern County, California, during the 2004 epidemic year and related to the duration of the Cx. tarsalis gonotrophic cycle and measures of WNV activity. Enzootic WNV activity commenced after temperatures increased, the duration of the EIP decreased, and virus potentially was transmitted in two or less gonotrophic cycles. Temperatures in the United States during the epidemic summers of 2002-2004 indicated that WNV dispersal and resulting epicenters were linked closely to above-average summer temperatures.
Author Reisen, W. K.; Fang, Y.; Martinez, V. M.
DOI 10.1093/jmedent/43.2.309
Date Mar
ISSN 1938-2928
Issue 2
Journal Journal of Medical Entomology
Keywords Animals; California; Culex/*virology; Encephalitis Virus, St. Louis/physiology; Encephalitis Virus, Western Equine/physiology; Female; Insect Vectors/*virology; Regression Analysis; Saliva/virology; Seasons; *Temperature; Time Factors; West Nile Fever/*transmission; West Nile virus/growth & development/*physiology
Notes Reisen, William K Fang, Ying Martinez, Vincent M eng 1-R01-AI55607/AI/NIAID NIH HHS/ Research Support, N.I.H., Extramural Research Support, U.S. Gov't, Non-P.H.S. 2006/04/20 09:00 J Med Entomol. 2006 Mar;43(2):309-17.
Pages 309-317
Title Effects of temperature on the transmission of West Nile virus by Culex tarsalis (Diptera: Culicidae)
Volume 43
Year 2006
Bibliographic identifiers
.reference_type 0
_record_number 18029
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